The transfer of electricity from power stations to substations and homes is done using transformers, power lines, cables, and other equipment. Grounding rods are set into the earth and connected into the network at various locations for safety purposes. Ground rods are often installed by driving them into the ground with a hammer or hydraulic ram. While the technique is often satisfactory for very loosely packed or soft ground, it is not satisfactory for many ground conditions, particularly since the rod is usuallly driven into the ground to a depth of eight feet or more. Often, the ground rod becomes bent during the installation process and is then driven at an angle to a relatively shallow depth rather than vertically to a depth that would provide better grounding.
Another method of setting the ground rod into the earth is to use an auger to drill a hole. After removing the auger, the ground rod is set in place and earth is repacked around it. This installation method has a couple of disadvantages. First, drilling the hole and then repacking it take a relatively large amount of time, thus making installation of ground rods by this method quite expensive. Second, for adequate grounding, the ground rod should be placed in undisturbed earth so that the earth tightly surrounds the rod. When the rod is placed in a hole and repacked with earth, the earth may not make sufficient contact with the rod to provide optimum grounding.
Another method in commercial use uses a ground rod in which an auger is fixedly mounted on the lower end of the rod. The ground rod is installed by placing it into a hollow shaft having threads at its lower end that are screwed onto the auger. Rotation of the shaft drives the ground rod into the earth, since the auger mounted at the lower end of the rod advances the rod downward into the earth. By rotating the hollow shaft coaxially in the opposite direction, the hollow shaft unscrews from the head of the ground rod and is drawn out of the ground for reuse. The principal disadvantage of using ground rods having permanently mounted auger heads is the relatively high cost of such ground rods.